1. Field of the Invention
The present invention relates to a method of washing laundry in a drum washing machine, and more particularly, to a method of washing laundry in a drum washing machine by which the amount of wash water used and the amount of power use can be reduced when doing washing.
2. Description of the Background Art
Generally, a washing machine is a machine designed to clean laundry by carrying out the steps of washing, rinsing and dewatering. According to a washing method, washing machines are classified into pulsator type machines, agitation type machines, drum type machines, and so on. Hereinafter, a general drum washing machine according to the prior art will be described with reference to FIG. 1.
FIG. 1 is a cross sectional view showing the construction of a drum washing machine according to the prior art.
As illustrated therein, the drum washing machine according to the prior art comprises: a cabinet 100 forming the appearance of the drum washing machine; a tub 110 arranged in the cabinet 100 for storing wash water; and a rotatable drum 120 arranged in the tub 110 for washing and dewatering laundry.
Hereinafter, the construction of the drum washing machine according to the prior art will be described in detail.
First, an inlet 130 for letting laundry enter and exit is formed on the front surface of the cabinet 100, and a door 135 for opening and closing the inlet 130 is disposed in front of the inlet 130. Further, the tub 110 is disposed in an anteroposterior direction in the cabinet 100. A plurality of support springs 140 and a plurality of dampers 150 are provided in the upper and lower sides of the tub 110 for cushioning and supporting the tub 110.
A detergent supply unit 160 is formed in the upper side of the tub 110 so as to supply detergent. Since the detergent supply unit 160 is connected to the tub 100, it can supply wash water and detergent to the tub 110. Further, a water supply pipe 170 with a water supply valve 180 is connected to one side of the detergent supply unit 160 so as to supply wash water. A drum driving motor 190 is coupled to the rear surface of the tub 110 so as to rotate the drum 120. A drainage channel 200 and a drainage pump 210 for drainage are provided on the bottom surface of the tub 110. A heater room 220 is formed at one lower region of the tub 110. A heater 230 is disposed in the heater room 220 for heating the wash water stored in the tub 110.
Meanwhile, a plurality of lifts 240, projected in the central axis direction of the drum 120 and extended in a direction parallel to the central axis of the drum 120, are formed on the inner surface of the drum 120 so as to move laundry upward and drop the laundry down.
A method of washing laundry in a drum washing machine according to the prior art will be described below. When a user starts the washing operation of the drum washing machine after putting laundry in the drum 120, the water supply valve 180 is opened to supply wash water into the tub 110 along with detergent. Thereafter, when the water level of the wash water reaches a set water level, the heater 230 is operated to heat the wash water, and simultaneously the drum 120 is rotated. Afterwards, when the temperature of the wash water reaches a set temperature, the heater 230 stops its operation and the drum driving motor 190 is operated until a set time, thereby carrying out the washing procedure. Here, when the drum 120 is rotated, the laundry in the drum 120 is moved upward by the lefts 240, and then dropped to a lower portion in the drum 120, thereby implementing the washing operation. Here, the heater 230 improves washing performance by heating the wash water at a temperature set according to the user's selection.
However, in the drum washing machine according to the prior art, as explained above, the heater room 220 is formed in a manner to be projected in a lower portion of the tub 110 in a downward direction so as to heat wash water, and the heater 230 is arrange din the heater room 220 so as to heat the wash water collected in the heater room 220. Thus, there is a problem that the amount of wash water used is increased because wash waster has to be additionally supplied in order to maintain a proper water level such that the heater 230 may be soaked in the wash water.
Furthermore, the drum washing machine according to the prior art has a problem that the amount of power use for heating the wash water is increased since the amount of wash water used is increased due to the aforementioned structure of the heater room 220 and heater 230.